The present invention relates to a method and composition for protecting a metal surface exposed to an oxidative environment.
Acidizing and fracturing treatments using aqueous acidic solutions commonly are carried out in hydrocarbon-containing subterranean formations penetrated by a well bore to accomplish a number of purposes, one of which is to increase the permeability of the formation. The increase in formation permeability normally results in an increase in the recovery of hydrocarbons from the formation.
In acidizing treatments, aqueous acidic solutions are introduced into the subterranean formation under pressure so that the acidic solution flows into the pore spaces of the formation. The acidic solution reacts with acid-soluble materials contained in the formation which results in an increase in the size of the pore spaces and an increase in the permeability of the formation.
In fracture acidizing treatments, one or more fractures are produced in the formation and the acidic solution is introduced into the fracture to etch flow channels in the fracture face. The acid also enlarges the pore spaces in the fracture face and in the formation.
A problem associated with acidizing subterranean formations is the oxidation or attack by the solution on the tubular goods in the well bore and the other equipment used to carry out the treatment. The expense of repairing or replacing damaged equipment is extremely high.
It would be desirable to provide a composition and method for treating a metal surface which reduces at least some of the oxidation problem resulting from contact of the oxidative environment with ferrous and other metals.